Mozilla today announced that Australis, a major user interface overhaul for its browser, has finally landed in the Firefox Nightly channel. The company calls it “the most carefully designed browser interface on the planet” and says it is “screaming fast.”

Aside from the visual improvements, Mozilla says it has also modernized its customization system. Firefox add-ons will still work as they always have, but it will be much easier to change the way Firefox looks and feels, the company promises.

It’s the most beautiful and detail-obsessed iteration of Firefox’s visual design yet: modern, clean, and comfortable.

More fundamentally, it’s a streamlining and simplification of the default interface, to declutter and better focus on how people use a browser today.

Finally, it includes a new simple way to customize the browser and make it your own.

If you prefer the more visual version, here’s a quick video that shows off Australis:

Mozilla also has an interactive mockup you can play with to try out Australis. We recommend simply downloading Firefox Nightly, however, given that it can be installed alongside Firefox.

Mozilla was first planning to have Australis ready for Firefox 25, which arrived last month. Firefox 26, which is slated for a December release, is currently in beta, so we know Australis definitely won’t be arriving this year.

The Firefox Nightly channel, as its name implies, is automatically updated each night: the builds are meant only for developers interested in helping out the company test new and experimental features. Firefox Nightly is currently on version 28,set to hit the stable channel in March, which means Australis is unlikely to arrive before then.